Automatic telephone system



W. T. POWELL. I AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED JULY 28.1919- 1 ,3 98,39 1 Patented Nov. 29, 1921.

CONNECTOR.

METER POLAR \ZED Um: SWlTCH INVENTOR ATTORNEY \MNFRED T. POWELL.

ilbllTliQ fi'lAlESr earner strict.

WINFRED T.1PO\VELL, OF ROCHESTER, NEW YORK, ASSIGNOR TO THE STROMBERG- CARLSON TELEPHONE MANUFACTURING A CORPORATION NEVI YORK.

COMPANY, OF ROCHESTER, NEW YORK,

AUTOMATIC TELEPHONE SYSTEM.

essee-i.

systems employing automatic switches for extending connections to various substations.

. Itis frequently desirable in telephone systerns to provide call charging means either in the form of message registers or coin collecting devices for charging for the service provided. In such arrangements as soon as thecalled party responds means are, pro vided for operating the service charging device. T his last named means frequently takes the form oi means for reversing the current to operate the polarized magnet of the meter and when such devicesare used in a telephone system, mechanisms must be provided for disabling them whenever a call is extended for which no charge is to be made.

The present invention has for its purpose the provision of means for disabling the call charging device of a subscribers line whenever this line is extended in completing a cal a for which no charge isto be made.

. Other features of the invention will appear from the detailed description and appended claims. i

The drawing diagrammatically represents a portion of the'telephonesystem incorporating one embodiment of thepresent inven tion. The left hand side ofthe drawing as far asthe dotted line represents a calling substation provided with a call charging device or meter, as well as the circuits or the line switch individual to this line, while the portion of the drawing between the dotted lines diagrammatically represents the operating circuits of a connector switch. At the upper. right hand corner of the drawing .there 18 indicated a called station which for the purposes of this disclosure has been rep resented as an'operatofls position provided with a well known listening key, operators head-set and signal for indicating extensions of calls to that position.

Specification of Letters Patent.

Patented Nov. 29, 1921.

Application filed July 28, 1919. Serial No. 313,878.

The line switch may take the form of any well. known rotary switch in which the contacts connected to outgoing lines are arranged in an arcuate bank and so positioned to coiiperate with brushes designed to be progressively advanced in a step-by-step man ner under the control of pawl and ratchet mechanism actuated by a motor magnet.

The line switch herein employed has a nori'nal position, but instead of employing a release magnet to restore this switch to its normal posit on when a call is abandoned, the

motor magnet is actuated to advance the brushes to their normal or home position. The connector switch herein referred to may be of a type similar to that disclosed in the patent to Keith, at at, 815,176, patented March 13th, 1906, when modified to operate in-aso-called two-wire system.

"he call charging device or meter is provided with a polarized magnet which is energized without effect on the initiation of a call. When, however, the called party a nswers the energizing effect of both windings of the magnet is cumulative to cause it to moves his receiver from its switchhook, the

line relay LR is energized in a circuit extending from grounded battery, resistance, line switch brush 2, inner lower back contact andarmature of relay 3, left hand winding of relay LR, through thesubstationcircuits,

left hand winding of the meter magnet 4L,

- upper armature and back contact of relay 3 and line switch brush 5 to ground. The line relay LR attracts its armature and thereby closes a circuit from ground, conductor 6, lower winding of slow-releasing relay 7, to grounded battery. Relay 7 attracts its armatures to close an energizing circuit for the relay 3, from grounded battery, lower winding of this relay, conductor 10, oil normal spring-and contact 8, inner-most lower armature and front contact of relay 7 conductor 6 to ground at the armature and contact ofthe line relay. An operating circuit forthe motor magnet MM is closed in multiple with the circuit just described extending Irom grounded battery, wmdmg, armaswitch. If this first trunk is already seized,

this condition will be indicated by the pres ence of ground on its terminal similar to 13, under which condition the relay 3 will be maintained energized in a circuit now closed Y from grounded battery, lower winding of at the test terminals of busy trunks.

this relay, its front contact and armature, test brush 14, test terminal 13 and through a multiple test terminal and test brush'simila-r to 14, through the lower-most armature'and back contact of a relay similar to 3 and through the right hand winding of a relay corresponding to line relay LR, to ground. The relay 7 is held energized in a circuit traceable i'rom grounded battery, upper winding, contact, and armature of relay 7, lower-most front contact and armature of relay 3 to ground over test brush 14,- and terminal 13. The motor magnet MM is also energized in a circuit completed over conductor 10, front contact and lower-most'armature of relay 3, to ground over test brush 14 and terminal 13.

It will be understood that the energizing circuits for relays 3 and 7 and for the motor magnet MM are successively completed But as soon as an idle trunk is reached, the relay 3 deenergizes and thereby interrupts the op erating circuits of the motor magnet MM and the energizing circuit ofthe slow-releasing relay 7. The relay 7, however, has a substitute holding circuit completed for itself over conductor 6 to ground at the front contact and armature of: the line relay LR which is againenergized as soon as a trunk is seized. Relay 3 on releasing also extends the line conductors to the connector and places a guarding potential on seized'trunk. As soon as the trunk whose conductors are indicated by the numerals 15 and 16 has been seized, the stepping relay SE of the connector is energized in a circuit closed :from' grounded battery, conductor 17, contact 18 and continuity spring, over the trunk conductor 16 and the lower side of the call- 'mg line, through the substation circuits and "upper side or" the calling line, trunk conductor 15, continuity spring and contact 19,

right hand winding of stepping relay SR,

to ground. The stepping relay SR is energized in this circuit and attracts its arma- "tureto close an energizing circuit for the "slow-releasing relay 20, and this relay at its'left handarmature opens the circuit of the release magnet REL, and at its right hand armature .and front contact closes a break point in the operating circuit of-the primary motor magnet PM.

The connector is now in condition to receive the impulses corresponding to the tens digit of the wanted number, and the calling 14, lower most armature and back contact of relay 3, and right hand winding of line relay LE to ground, and is then induced in the left handwinding of the line relay LR and from thence through the substation circuits of the calling line. now operates his dial in accordance with the tens digit of the wanted number causing the stepping relay SR to vibrate its armature, thereby maintaining the slow-releasing relay' 20 actuated, and at its back contact closes a circuit from ground, right hand front contact and armature of relay 20, winding of the slow-releasing relay 21, side switch wiper 22 in its first position, winding of the primary motor magnet PM, secondary winding'of the induction coil, to grounded battery. In response to the first impulse, the slow-releasing relay 21 is actuated and remains actuated during this series of impulses to hold the escape magnet ESQ actuated in a circuit traceable from grounded battery, resistance, winding of the escape magnet, continuity spring and armature of relay 21, to ground.

The calling party 'i-Xtthe close of the tens series of impulses,

the stepping relay SR attracts itsarmature for a relatively long interval so that the slow-releasing relay 21 deener'gizes to open 'the circuit of the escape magnet, causing this magnet to move the side switch wipers into their second position. The calling party then operates his dial and sends a series of impulses corresponding to the units digit of the wantednumberg- In response to this series of impulses, the stepping relay SR again vibrates'its armature, but in this instance it'closes an operating circuit for the secondary motor magnet SM, from grounded battery, secondary winding of the induction coil, winding of the secondary magnet, lower armature and back contact pf test relay TEST, also switch wiper 22 1n its second position, winding of relay 21, right hand armature and front contact of relay- 20, back contact and armature of stepping relay SR, to ground. In response to this series of impulses, the secondary magnet SM advances thebrushes 23, 24 and "-25 in its right hand winding, front contact and of relay line. i

, Since it is not necessary to register the call that has been extended to the operator,

their secondary movement to select the wanted hne. At the first impulse of this series, relay 21. attracts its armature and holds t operated during the series so that the operating circuit ofthe escape magnet ESQ preriously described, is completed. At the close of the units series ofimpulses if the called line is idle, the escape magnet ESQ dcenergizes and moves the side switch wipers into their third position.

If the call had been extended to a suhscriber, it would have been necessary to apply ringing current to thewanted line to operate the call bell. at the substation, but since the call has been extended to an operators position it is not necessary to supply the ringing current for signaling'purposes. I It is therefore only necessary to p erate the trlp magnet TRIP to move the side switch wlpers into their fourth posltion. This is .accomplished in the following manner: As soon as the side switch wipers circuit, but itsleft hand armature is slow to respond while its right hand armature is quick acting and closes a locking circuit for this relay from groi'inded battery,

armature, conductor 31, test brush 25, side switch wiper 32 in its third position to ground. The trip magnet TRIP is enerized in series with the lefthand winding 29 and attracts its armature to short circuit the escape magnet. The escape magnetESC moves the side switch wipers into the fourth or talking position. As soon as the side switch-wiper 32 reaches position and also position 4:, a circuit is closed for-the lamp at the operatoris position, from grounded battery, armature and back contact of relay 34:, conductor, 31, test brush 25, and sideswitch wiper 32, to ground. The lamp 33 informs the operator-that a call is awaiting attention at her. posltlon whereupon she presses the listening key LE, to connect her telephone set to the extended the meter associated with the calling line must not be operated. The magnet i of the meter is polarized and is operated by a re versal of current when the called party answers. In an ordinary connection forwhich a charge is made, a relay similar to 35 at the connector attracts its armatures and thereby reverses the direction of the current in trunk conductors l5 and 16. Since it has been assumed that the call has been extended to an operators position, the relay 35 must not bring about this reversal of current. By reference to the diagram it will be seen that in the present connection the conductor extending from the left hand winding of the relay 35 is open, whereas theright hand winding of the relay 35 is included in a circuit extending from ground to ground.

ltwill be noted by reference to the drawing that,when a trunk leading to an operators position is selected and when the operator has thrown her listening key, the two sides of this selected trunk are conductively separated by means of the condenser in series with the operators receiver. Therefore the battery feed relay 35 of the called. end of the trunk is not operated with'theresult that the polarized meter magnet 4 of the calling line will not be actuated. Since the two sides of the trunk of the operators position are thus conductively separated some means must be provided for tripping the ringing current. This means which has been pointed out is the relay which is effective to trip the ringing as soon as the operators position has been selected. It will also be noted that as soon as the relay 29 is operated it. is locked in this condition over conductor 31 thus preventing the unbalancing of the conversational circuit.

Let it be assumed that the line leading to the operators position is busy when the brushes 23, 24 and 25 were placed in operative relation to its terminals; It will be remembered that at this time the escape magnet ESC had its operating circuit closed to ground atthe armatureofi relay 21, and when the armature of relay 21 is retracted at the close of the units series of impulses, the escape magnet ESC is maintained energized in a circuit traceable from grounded battery, resistance, winding of the escapemagnet ESQ, continuity spring "and contact of relay 21, winding of the test relay TEST, continuity spring and contact of this relay, sideswitch wiper 32 in its second position, test brush 25, through the inultipleftest terminal of the wanted line, through test brush similar to 25, anda side switch wiper similar to 32 in its fourth position at the connector which has previously seized the called line. The

t test relay TEST attracts its armatures, and

at its continuity spring and front contact closes, alocking circuit for itself in series with the escape magnet ESQ, to ground, through contact and of]? normal spring. At

t e innerm st a atu n t eat was lOQ of the test relay, a busy tone is applied to the calling line from the busy machine B Z.

When the calling subscriber terminates the call by replacing his receiver on the switchhook, stepping relay SR deenergizes to interrupt the operating circuit of the slow-releasing relay 20. The relay 20 retracts its armatures and closes a circuit for the release magnet REL from grounded bat tery, winding of this magnet, ofl' normal spring and" contact 36, back contact and armature of relay 20 to ground which releases the connector switch. The line relay LR at the line switch also retracts its armature permitting the slow-releasing relay 7 to release. This closes an operating circuit for the motor magnet MM from grounded bat- "motor magnet.

Although no selector switches have been shown in the present disclosure, it will be readily understood that in large systems,

such selectors will be interposed between the line switches and connectors as indicated at the dotted portions of conductors 15 and 16. WhatI claim is: '1. In a telephone system, a plurality of telephone lines, a service charging device as- 'sociated with certain of said lines, means 'for extending any one of said lines to any 7 other line, means operative during the extension of a callfrom a telephone line provided with a service charging device to certain lines for operating said service charging device, and means including an electromagnetic device having elements operating in diiferent time intervals to disable said last .mentioned means when no charge is to be charge is to be made.

Linade. V

In a telephone system, a plurality of telephone lines, a service charging device associatedwith certain of said lines, means for extending any one of saidl nes to any other line, means operative during the extension ofacall from, a telephone line provided with afservicecharging device to certain lines for operating said service charging device, and means including a relay having fast and slow operating armatures functioning to dis- .able said last mentioned means when no 3, In a telephone system, a plurality of telephone lines, a service charging device as- I sociated with certa n of said lines, means for extending any one of said lines to any other 1 line, means operativedulfing the extension of a call from'a telephone line provided witha service charging device to certain lines for operating said'service charging device, and means includlng a relay having armatures operating in difl'erent time intervals to disable said last mentioned means. a

4. In a telephone system, a plurality of telephone lines, a service charging device associatedwith certain of said lines, means for extending any one of said lines to any other line, means operative during the extension of a call from a telephone line provided with a service charging device to certain lines for operating said service charging device, and means including a relay for disabling said last mentioned means when no charge is to be made, said relay having two windings, one winding to initially energize said relay, and the other winding to maintain said relay actuated when once energized.

5. In a telephone system, telephone lines, service charging means for certain lines, operating to charge for the extension of any one of said lines to any other line, and discriminating means including an electromagnetic devicehaving two elements operating out'of synchronism to determine whether or not said charging devices will be operated.

6. In a telephone system, telephonelines,

service charging means for certain lines, operating to charge for the extension of any one of said lines to any other line, and adiscriminating means for each of several lines, said discrimnating means including an electromagnetic device having two elements operating out of synchronism to determine, whether or not said charging devices wlll be operated.

7. In a telephone system, a plurality of telephone lines, means including automatic switches for interconnecting said telephone lines, a service chargingdevice for eachof certain of said lines, said device being actuated by a, reversal of current, means for applying signaling current to and dlsconnecting same from a selected line, mechanism responsive to the completion of a call to certain'of said telephone lines for reversing the current'to the service charging device of the calling line to v actuate the same and means including a relay" having a'rmatures acting out or" 'synchronism to disable said mechanism and to operatesaid signaling current disconnecting means.

8. In a telephone system, a plurality of telephone lines, one or more operatorslines, a service chargingdevice for each of said telephone lines arranged to be actuated by a reversal of current, mechanism for connecting signaling current to and disconnecting the same from, a selected line, a device actuated by the completion of a'connection over a selected telephone line for operating said service charging dedvice and actuating said mechanism and means including an electromagnetic device having elements operating out of synchronisrn associated with each operators line for disabling said device and for operating said mechanism.

9. In a telephone system, a plurality of telephone lines, one or more operators lines a service charging device for each of saic telephone lines arranged to be actuated by a reversal of current, a multi-position switch for connecting signaling current to and disconnecting the same from a selected telephone line, a device actuated by the completion of a connection over a selected telephone line for operating said service charging device, and actuating said multi-position switch and means including an electromagnetic device having elements operating out of synchronism associated with each operators line for disabling said device and for operating said multi-position switch.

10. In a telephone system, a plurality of telephone lines, one or more operators lines, a service charging device for each of said telephone lines arranged to be actuated by a reversal of current a side switch for connecting signaling'current to and disconnect ing the same from a selected telephone line, a device actuated by the completion of a connection over a selected telephone line for operating said service charging device, and

actuating said side switch and means including an electromagnetic device having elements operating out of synchronism associated with each opera'tors line for disabling said device and for operating said side switch.

11. In a telephone system, a plurality of telephone lines, one or more operatorslines, a service charging device for each of said telephone lines arranged to be actuated'by a reversal of current, a double wound relay through which talking battery is supplied to the called end of a connection, said relay being operated 011 the completion of a call to a telephone line to reverse the current and to actuate the service charging device of the calling telephone line, a source of signaling current and a switching device for connecting said source of signaling current to and disconnecting the same from a selected line and means including an electromagnetic device associated with each operators line for disabling saidrelay and actuating said switching device to disconnect the source of signaling current from the selected line.

In witness whereof, I hereunto subscribe my name this 26th day of July, A. D. 1919.

WINFREDT. POWELL. 

